Temperatures of up to 40 degrees Celsius are being recorded in the country
At least 62 people have died in forest fires in Portugal, officials say.
Many of the victims were trapped in or near their cars as they tried to escape the flames.
A blaze has been raging in Pedrogao Grande - a mountainous region in the centre of the country, around 150 kilometres northeast of Lisbon.
Officials say a lightning strike is believed to have sparked the blaze.
Interior Ministry official Jorge Gomes said 16 people lost their lives in their vehicles between the towns of Figueiro dos Vinhos and Castanheira de Pera.
"The smoke cloud is very low, which does not allow helicopters and fire planes to work efficiently, but we're doing everything possible and impossible to put out this fire, " he said.
Hundreds of firefighters are battling to keep the blaze under control, local media reports.
Dozens of others are said to have been injured, with six firefighters reported to be among those hurt.
It is feared the death toll could rise further
In comments quoted by AFP, Portuguese Prime Minister Antonio Costa said: "Unfortunately this seems to be the greatest tragedy we have seen in recent years in terms of forest fires."
The fires come as temperatures soar in Portugal, with officials warning the public of temperatures of up to 40 degrees Celsius.
Some 60 forest fires broke out across the country overnight on Saturday.